Dental needle shield



1955 R. c. VANDERBECK Filed Nov. 1, 1965' A lil'lwm a INVENTOR. c. VANDEREACK protection for the user. sterile'and protection must be provided for the user when United States Patent '0 3,294,231 DENTAL NEEDLESHIELD Russell C. Vanderbeck, Saddle River, NJ., assignor to -Becton Dickinson and Company, EastRutherford, N.J.,

a corporation of New Jersey Filed Nov.1, 1965, Ser. No. 505,889 1 Claim. (Cl. 20663.2)

This invention relates to a cap assembly for covering one end of a hypodermic' need'le or cannula; particularly one end-of a double ended needle such asa dental cannula. More particularly, the invention relates to a cap which is mounted upon a cannula hub by a straight axial force imparted thereto yet is removed *by unthreading the cap from the hub.

Packages containing medical apparatus, such as contemplated herein, aregenerally sealed so as to keep the contents in a sterile condition prior to use and to provide The needles must also remain the needle is removed from its envelope before being mounted upon the ampule stopper of a hypodermic syringe for subsequent use. To provide for protection and maintain sterility, it is contemplated'to encase the cannula by a suitable cap structure.

-It is therefore-an objectof this invention to provide a cap that may be easily mountedupon the supporting hub such as a dental needle and which cap is. removably mounted on a rigid supporting hub portion of a cannula. The cap is formed of a relatively yielding material and provided with a plu'rality'of longitudinally extending and circumferentially spaced external ribs that are adapted to interact with an internal threaded surface'formed on the hub to provide a relatively-tight fitwhen the parts-are assembled, said cap being received on the hub by means of a straight axial force imparted thereto which results in threads being impressed in the ribs when the parts are tightly engaged with each other whereby the cap is removed by unthreading one part from the other.

In the accompanying drawings which both illustrate a preferred embodiment of the invention and form a part of this application,

FIGURE 1 is a plan view of a packaged double ended cannula or dental needle assembly with the improved cap in surrounding relation to one puncture end of the rigidly mounted cannula;

FIGURE 2 is an exploded view partially in cross-section of the cannula, its supporting hub and cap;

FIGURE 3 is an end view of the cap as seen in FIG. 2 and showing a plurality of upstanding interference ribs;

FIGURE 4 is a view similar to FIG. 2 with the cap and hub in assembled relation; and

FIGURE 5 is a fragmentary, longitudinal sectional view of the open end of the cap after removal from the hub, showing a set of threads tapped in the ribs.

Referring now to the drawings, FIG. 1 generally shows a sealed package and its contents all denoted by the numeral 10. The contents comprise a dental needle hub 12 which immovably supports a cannula 14 at a point between its ends, a shield or sheath 16 encircling the long body piercing portion of the cannula, and a cap 18 covering available. "be formed. by a. molding or equivalent process and may a be .formed so as to provide a central opening extending theishorter'cannula end which-is vadapted to pierce the stopper of 1a hypodermic ampule. -As is well known in the. art, the needle assembly issterilized before or after packaging ;by, .as for-example, ethylene oxide and the assembly will'retain such sterility for a. reasonable time *While within the. package.

The hub 12 which is shown to best advantage in FIGS. 2 and 4.is.generally cylindrical in shape and formed from one of the relatively hard, rigid non-yieldable plastic materials such as polystyrene, a high molecular weight polypropylene, etc., or metal, all of which are commercially The hub is of unitary constructionand' may therethrough forreceipt of the cannula 14. As is noted in. FIG. 2, the central opening is formed with cavities 20 which may be filled with an epoxy resin to essentially .weld.the cannula to the hub and fixedly secure the cannula in the desired position. Obviously, one skilled in .the art will contemplate additional methods for fixedly securinga metal cannula to a plastic or metal hub, the

" method discussed being merely exemplary.

' Thehub is formed with an annular sleeve portion 22 that extends in one, longitudinal direction and a circular neck. portion'24 extending in the other longitudinal direction and having azneedle receiving opening extending .therethrou'gh. Thexneck has ,an outer diameter which is i substantiallyequal to the inner diameter of the sleeve and each constitutes approximately one half of the hubs total :length.

Threads 26, are formed on theinner cylindrical wall of .the sleeve with the threads extending from a point near the'open end to approximately the bottom of the sleeve.

Since thehub is of a rigid non-yielding material, the thread will retain its shape and act as a self-tap to positively receiveand hold the cap 18, as will-bebrought outbelow.

'A plurality of longitudinally extending ribs 28 are formed-on the outer portion of the neck 24. It is preferred to providejthe neck with three or four ribs that are circumferentially. spaced to allow foraxial receival of Therefore, with the sheath the sheath to precludeysubstantially all-'rotaryzmovement between the parts when assembled, with the ribs, further, creating a good frictional hold between the parts.

As shown in FIG. 1 the sheath 16 carries a plurality of longitudinal corrugations 30 which may be gripped in a positive manner so that the sheath may function as a wrench in the manner hereinafter indicated.

As generally brought out above, a cap 18 is provided to encase the short cannula portion prior to aflixing the hub and cannula to the ampule of a hypodermic syringe. As is apparent, both the sheath and the cap not only provide extra protection for the needle and the user before, during and after use of the cannula, by encasing the exposed puncture points, they also keep the cannula in its sten'le condition during the interval between its removal from the package and use.

The cap 18 is generally in the form of a hollow truncated cone terminating adjacent the open end in a collar 32 from which extends a sleeve portion 34. The sleeve is generally cylindrical in shape and is relatively thin in cross-section. Further, the shield is formed of a relatively softer and less rigid plastic which is more flexible and yielding than the relatively hard and rigid hub. The cap, for example, may be formed of polyethylene which possesses these qualities.

A plurality of raised ribs 36, as best seen in FIG. 3, are formed on the exterior cylindrical surface of the sleeve, and which ribs extend the longitudinal length of the sleeve.

While any greater number of ribs may be provided, sufficient interaction between the ribs 36 and threads 26 is developed by having three ribs which are angularly spaced around the peripheral surface of the sleeve.

To provide a protective assembly which may be handled Without the exposure of the sharp cannula points the shield 16 is axially placed upon the neck portion 24 of hub 12 so that the respective ribs reside in the respective grooves on each part. inner diameter of the shield) are chosen so that a relatively tight fit is provided therebetween and the parts are assembled by an axial force. Thereafter, the cap 18 is mounted on the hub and it should be noted that these parts are also connected by the application of a straight axial force to the cap until a tight interference fit is obtained between the threads and ribs. The parts will be, thereafter, firmly held in assembled association by interference between the ribs and the internal hub thread 26. The unit is therefore in unitary form and the fit between the respective parts is such that they will not jar loose during normal handling. Further, the unit may be distributed within a sterile package and the relatively tight fit of the parts will maintain them in position.

To use the device it is to be noted that the cap 18 is first removed from the hub by a relative rotary unthreading movement between the parts since an axial force imparted to the cap will cause the hub to release from shield 16, leaving the hub and cap connected. This occurs due The diameters (outer diameter of the hub and to fact that the cap is more positively secured to the hub than is the shield. The tight fit is provided due to the resilience of the sleeve 34 which, after yielding inwardly during assembly on the hub, tends to return to its initial cylindrical configuration with the ribs 36 substantially conforming, in a complementary fashion, to the configuration of the threads 26. Such is shown in FIG. 4.

In FIG. 5 it is seen that the relatively hard threaded portion 26 has essentially tapped a thread in the relatively softer ribs 36 as the cap is threadedly removed from the hub. The tapped thread is shown at 38.

To mount the hub and cannula 011 the syringe, the cap 18 is removed, as discussed above, and the short portion of the cannula forced through the easily pierceable stopper of the ampule. The shield 16, which is still in place, may be used as a wrench, since relative movement between the shield and hub is prevented by the interacting ribs, and the hub may be threaded on the ampule that is suitably provided with a complementary thread. Once the union is accomplished, the shield 16 is removed and a medical injection may be made.

From the foregoing it is obvious that a unique dental needle cap is provided and which accomplishes the here inbefore stated objects. The cap is simple in construction yet operates to create a relatively firm fit on the dental hub when in surrounding relation of the cannula and is removable by unscrewing it from the hub.

While the invention has been particularly shown and described with reference to a preferred embodiment there of, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims.

Having described the invention what is claimed is:

A sterile disposable needle assembly adapted for use with a hypodermic syringe comprising a substantially rigid hub element having a longitudinal opening therethrough and including an annular skirt portion and a neck portion integral therewith and extending in opposite longitudinal directions, said neck portion carrying a plurality of longitudinal extending and circumferentially spaced ribs, said annular portion carrying an internal relatively rigid thread, a cannula rigidly and sealingly received within said longitudinal opening of said hub whereby the ends of the cannula extend outwardly of said annular skirt and neck portions, a sheath member received on said neck in surrounding relation to one of said cannula ends and frictionally retained by said neck ribs, a yieldable cap adapted to be received within said annular portion in surrounding relation to said other cannula end, and means on said cap for mounting the latter to said annular portion comprising a plurality of longitudinally extending and circumferentially spaced ribs of less rigidity than the thread formed on the annular skirt portion whereby said cap is received on said hub by a straight axial force causing the open end to yield inwardly thereafter returning to its original shape to be retained by the interaction of said ribs and thread in assembled position for removal by an unthreading force.

References Cited by the Examiner UNITED STATES PATENTS 2,058,297 10/ 1936 Carvalho 215-44 2,597,830 5/1952 Webb 215-44 2,991,136 7/1961 Eichmann 21543 LOUIS G. MANCENE, Primary Examiner.

THERON E. CONDON, Examiner.

J. M. CASKIE, Assistant Examiner. 

